Fiameni Laura, Fahimi Ario, Marchesi Claudio, Sorrentino Giampiero Pasquale, Zanoletti Alessandra, Moreira Karen, Valentim Bruno, Predeanu Georgeta, Depero Laura Eleonora, Bontempi Elza
INSTM and Chemistry for Technologies Laboratory, Department of Mechanical and Industrial Engineering, University of Brescia, Via Branze, 38, 25123 Brescia, Italy.
Instituto de Ciências da Terra (ICT), Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre 1021, 4169-007 Porto, Portugal.
Materials (Basel). 2021 Oct 22;14(21):6297. doi: 10.3390/ma14216297.
Phosphate rocks are a critical resource for the European Union, and alternative sources to assure the future production of a new generation of fertilizers are to be assessed. In this study, a statistical approach, combined with a sustainability evaluation for the recovery of materials from waste containing phosphorus (P), is presented. This work proposes a strategy to recover P and silica (SiO) from rice husk poultry litter ash (RHPLA). The design of experiment (DoE) method was applied to maximize the P extraction using hydrochloric acid (HCl), with the aim to minimize the contamination that can occur by leachable heavy metals present in RHPLA, such as zinc (Zn). Two independent variables, the molar concentration of the acid, and the liquid-to-solid ratio (L/S) between the acid and RHPLA, were used in the experimental design to optimize the operating parameters. The statistical analysis showed that a HCl concentration of 0.34 mol/L and an L/S ratio of 50 are the best conditions to recover P with low Zn contamination. Concerning the SiO, its content in RHPLA is too low to consider the proposed recovery process as advantageous. However, based on our analysis, this process should be sustainable to recover SiO when its content in the starting materials is more than 80%.
磷矿石是欧盟的关键资源，需评估确保新一代肥料未来生产的替代来源。本研究提出一种统计方法，并结合从含磷（P）废物中回收材料的可持续性评估。这项工作提出了一种从稻壳家禽粪便灰（RHPLA）中回收P和二氧化硅（SiO）的策略。采用实验设计（DoE）方法，以盐酸（HCl）最大化P的提取，目的是尽量减少RHPLA中可浸出重金属（如锌（Zn））可能造成的污染。实验设计中使用了两个自变量，即酸的摩尔浓度和酸与RHPLA之间的液固比（L/S），以优化操作参数。统计分析表明，0.34 mol/L的HCl浓度和50的L/S比是回收P且锌污染低的最佳条件。关于SiO，其在RHPLA中的含量过低，因此所提出的回收工艺并无优势。然而，根据我们的分析，当起始材料中SiO的含量超过80%时，该回收SiO的工艺应具有可持续性。
